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Connection Backflow preventer (brass?) to PVC fitting = leak !!!

I just installed my 5-zone manifold system using 900 ft of 1-inch PVC. Everything looks great, works well...except I have 2 slow drip leaks that I'm compelled to fix. Both are a brass (?) ball valve female-threaded fitting to PVC male thread (one on main stop valve and other is on one end of the backflow preventer). I've put Teflon tape on the male threads, but only 1 layer deep. I've now done this twice (the second time I reconstructed the entire glued elbow (adapter-to-elbow-to-union) which is easy to dissassemble because I used a union in front and behind my backflow preventer (for easy winterization = bring it inside). I'm starting to think, and read online in several forums suggesting that teflon paste should be used on metal-to-PVC fittings of 1-inch or greater? Is this the trick? I may try 3-4 wraps of teflon tape first as I've now seen those suggestions whereas I've only used 1 wrap, trying not to double wrap anywhere (which seems like the wrong thing to do from what I'm seeing posted?). Any comments are appreciated. All my glue connections are great!

I have a similar situation where the thread to the valve leak very slowly (even though I used teflon tape) and tighted it very tight. I am starting to wonder if it is possible to over tightening it and possibly caused a crack (I used a wrench)?

Anyways, just curious if you found out if the small leak plugged itself up (got better) or if the leak got worst over time or if the small leak remained the same and you considered it good enough since it was out doors (in my case, the spinkler valve)?

Thanks!

Even if an irrigation system is "outdoors", if the leak in question is in a mineline (pipe under constant pressure) then that is unacceptable [to me] because it leaks 24/7. So a small leak on the output side of a valve might be tollerable, but a leak on the input side (that's under constant pressure from city water) is not.

In the time since this post was created, I've been able to install an irrigation/drip irrigation system around my house. I never did learn a procedure that would reliably create a leak-free connection, here's what I found worked most often:

Wrap the threads with teflon tape for 5 to 7 wraps. Before you screw the parts together, pre-seat the tape in the threads. For example, the thing I would usually do is cover my hand with a rag and make a loose fist. I would then try to screwn the taped threads into my hand (the "hole" between my thumb and fingers). Then proceed to screw the final pieces together.

To avoid splitting the connection, the rule of thumb is to tighten my hand, then use a wrench to tighten about 1/2 turn (1 full turn max). And if you are ever having to join PVC to metal, the PVC MUST be a male and the metal a female.

I doubt Segask will make an appearance since his post is 7 years old. To answer your question you can definetly over tighten and break the plastic. Also all three of your questions are possible. It might stop. It might get worse, a lot. It might stay the same.

Can you tell me what model valve it is and what do you have screwed into it?

Just by off chance you used a Spears male adapter there's a problem with them cracking due to brittle plastic. They used to be an excellent fitting then Spears redesigned them.

I have a similar situation where the thread to the valve leak very slowly (even though I used teflon tape) and tighted it very tight. I am starting to wonder if it is possible to over tightening it and possibly caused a crack (I used a wrench)?

Anyways, just curious if you found out if the small leak plugged itself up (got better) or if the leak got worst over time or if the small leak remained the same and you considered it good enough since it was out doors (in my case, the spinkler valve)?